[gdb/python] Eliminate catch(...) in type_to_type_object

In type_to_type_object we have:
...
  try
    {
      if (type->is_stub ())
	type = check_typedef (type);
    }
  catch (...)
    {
      /* Just ignore failures in check_typedef.  */
    }
...

The catch is supposed to ignore gdb_exception_error, but it ignores any
exception.

Fix that by only ignoring gdb_exception_error, and handling
gdb_exception_quit / gdb_exception_forced_quit using GDB_PY_HANDLE_EXCEPTION.

Tested on x86_64-linux.

Approved-By: Tom Tromey <tom@tromey.com>